Is the certainty of saving a life today worth more than the less-certain possibility of saving 10 lives tomorrow? In six pre-registered studies with U.S. samples from Prolific (N = 5,095), we employed an intergenerational probability discounting task, discovering people discount the value of life as uncertainty and intergenerational distance from the present increase. Specifically, as uncertainty about impacting the future rises, individuals increasingly prioritize saving fewer present lives over more future lives, particularly for more distant future beneficiaries (Studies 1-2b). Experimental evidence (Studies 3a-4) suggests that certainty perceptions drive intergenerational concern, rather than the inverse. Drawing upon seminal research from cognitive science and behavioral economics, these findings address gaps in emerging social psychological inquiry into long-term intergenerational concern, shed light on mechanisms underlying debates on the ethical philosophy of longtermism, and highlight practical implications for decision-makers, stressing the need to increase certainty perceptions surrounding about pro-future actions to enhance intergenerational beneficence.
Keywords: decision-making; ethical philosophy; intergenerational discounting; intergroup processes; longtermism; motivated bias.